↵aE. coli S17-1λpir was used as a donor strain. The values are the averages of three independent mating experiments.

↵b Frequencies of recipient cells that received the Kmr determinant. Frequencies were calculated by dividing the number of Kmr transconjugants obtained by the number of recipient cells counted immediately after conjugation. Transconjugants were selected on MBM plates supplemented with succinate and kanamycin. Recipient strains were counted on MBM plates supplemented with succinate. The percentage of Kmr transconjugants that also acquired the Apr determinant of the vector is indicated after each value in parentheses.

↵c Frequencies of recipient cells that received the Apr determinant. Frequencies were calculated by dividing the number of Apr transconjugants obtained by the number of recipient cells counted immediately after conjugation. Transconjugants were selected on MBM plates supplemented with succinate and ampicillin. Recipient strains were counted on MBM plates supplemented with succinate. The percentage of Apr transconjugants that also acquired the Kmr determinant of the vector is indicated after each value in parentheses.